My first finished map. It was not made with a DM map layout in mind, so it may not be a very good DM map. It's mostly just for walking around in. It's also very unoptimized, so some people may have trouble running it. The .rar inclues some custom resources that this map needs. I did not create the custom resources myself.
I agree that, in its current form, it's not really suitable for DM. The layout is too linear and the doors, narrow doorways and various protrusions hinder fast movement. If you want to make a 'proper' DM map, I'd suggest creating a 'blockout' level that focuses entirely on layout and gameplay. Keeping it visually simple allows you to make gameplay tweaks more easily. Once you're satisfied with the gameplay, start decorating it, using this map as a style guide.
As for optimizations, maybe you know some (or all) of this already, but just in case, here are some of the things that you can do:
gl_wireframe 1
console command to look for areas with lots of face splitting (typically near rounded shapes), and see if you can reduce that with a func_detail or some other trickgl_wireframe 2
to see which areas are visible at any given moment, and adjust the layout to ensure that not too much it visible from any given position (maps often use U-bends in corridors to block visibility between areas)